The present invention relates generally to a vehicular tracking system, and, more particularly, to a system and method for tracking a vehicle performance while competing in the current GPS Racing Games using a Global Positioning System, an Inertial Navigation System and a transceiver for communicating location information to a centralized processor for the purpose of measuring and comparing vehicle performance.
The Global Positioning System (GPS) currently in service utilizes an artificial constellation of between 24 and 32 Medium Earth Orbit satellites which transmit precise microwave signals. These signals enable GPS receivers to reckon navigation data including location, speed, direction and time using a spread spectrum system. The reckoning is carried out on the Earth by receiving GPS signals from a plurality of satellites, for example, by receiving GPS signals from three satellites for two-dimensional positioning and from four satellites for three-dimensional positioning. In this way, based on the navigation data contained in the GPS signal from each satellite, position information on the receiving point such as a latitude, longitude and altitude thereof can be determined in near real time.
The GPS system was originally developed for U.S. military use, however, a part of the GPS signal has been made available for civil use. Therefore, it is possible to build navigation systems for vehicles using the GPS signal. In operation, a GPS receiver used for a vehicle-mounted navigation equipment starts a search operation to capture the signal from a GPS satellite when the system is first activated. A GPS receiver may also need to recapture the GPS satellite when the vehicle emerges from a tunnel for example, and the reception of the GPS signals from the GPS satellites is interrupted for more than a specified period of time (for example, one minute). The satellite signals, as mentioned above, are transmitted by the spread-spectrum system. To reckon a position the GPS must be initiated; a satellite signal must acquired and the spread spectrum signal “despread” to determine location information. This process induces a delay limiting the GPS's ability to provide real time position information. Because of this delay, the conventional GPS receiver is not capable of dealing with an interruption of the received signal, such as when the vehicle is in the tunnel. It takes a considerable time for the GPS receiver to recapture the GPS satellite after the vehicle passes through the tunnel thus causing a problem in positioning. Also the ability of a GPS to provide real-time position information is limited to about once per second by the frequency of the passing satellites, thus a short burst of acceleration may not be appropriately reckoned. Because of these limitations inertial navigation systems are used to provide more accurate location information.
Inertial navigation systems are well known in the art and are used to provide real-time position information. A typical inertial navigation system integrates the information gathered from a combination of gyroscopes and accelerometers to determine the current state of the system. Gyroscopes measure the angular velocity of the system in the inertial reference frame. By using the original orientation of the system in the inertial reference frame as the initial condition and integrating the angular velocity, the system's current orientation is known at all times. Accelerometers measure the linear acceleration of the system in the inertial reference frame, but in directions that can only be measured relative to the moving system. By tracking both the current angular velocity of the system and the current linear acceleration of the system acceleration of the system in the inertial reference frame. Performing integration on the inertial accelerations and velocities yields the inertial state of the system. All inertial navigation systems suffer from small errors in the measurement of acceleration and angular velocity which in turn are integrated into progressively larger errors over time. Often inertial navigation is used to complement GPS, providing a higher degree of accuracy. By properly combining the information from an inertial navigation system and the GPS, suitable vehicle position can be determined.
The best known use of the GPS system is as an automotive navigation system. This satellite navigation system designed for use in automobiles uses a GPS navigation device to acquire position data to locate the user on a road in the unit's map database. Using the road database, the unit can give directions to any other selected locations along roads also in its database. Dead reckoning using distance data from sensors attached to the drive-train, a gyroscope and an accelerometer can be used for increased reliability, as GPS signal loss and/or multipath can occur due to urban canyons, tunnels or other natural and artificial conditions interfering with the GPS signals.
In view of the foregoing, a combined GPS and inertial navigation system can allow for providing accurate location information on racing vehicles. Racing is known for its severe accidents resulting from frequently occurring collisions amongst the competitors and other difficulties caused by a physical interference of one competitor on another. Thus, it would be advantageous to have a means to race vehicles without requiring the vehicles vie for the same physical space at the same time. As such, what is needed is a means to collect, record and compare vehicle position information combined with objective vehicle and race driver data for the purposes of determining a performance in a vehicle competition.
The Vehicle Tracking System and Game enables various users to compete with each other by comparing their location histories, their performance and achieved results on different race tasks, and their user data. The competitors do not need to be physically present at the same time but a server collects the users' data transmitted from the users' vehicles mobile unit to a database and determines the winner based on a comparison of their race data. This enables various types of games based on time, speed, maximum acceleration, stopping distances, consistency, skillfulness, or other performance parameters and racer information. The GPS racing systems comprises an Inertial Navigation System, a GPS, and a remote database and webserver.